Auto worker Ivan Flores spends his days transporting parts for U.S.-bound Audi SUVs at a plant in central Mexico, but he laughs when asked if he could ever buy one of the $40,000 Q5 SUVs the plant produces on his $2.25 per hour salary.

Scandals. Recalls. Threats of bans. The diesel engine is a public enemy for many environmental activists and politicians. And yet, when the world's biggest automakers unveil new models at this year's auto show in Frankfurt, among the new electric vehicles and digitally enhanced prototypes there will also be diesel cars.

Judging by the slew of electric and hybrid vehicles being rolled out at the Frankfurt Auto Show, it might seem carmakers are tapping a large and eager market. But in fact almost no one buys such cars – yet.

Germany’s car industry, the backbone of Europe’s largest economy, is booming again. Fueled by the huge appetite for German luxury cars in China and the fact that the plunging euro has made European products cheaper abroad, manufacturers say they are shaking off the last of the economic downturn, adding extra shifts and hiring more workers to meet increasing demand.